io: combine _io.TerminalWriter and _io.terminalwriter.TerminalWriter

Previously it extended an external type but now it come move to the type
itself.

src/_pytest/_io/__init__.py

@@ -1,39 +1,6 @@
-from typing import List
+from .terminalwriter import TerminalWriter
-from typing import Sequence
-
-from .terminalwriter import TerminalWriter as BaseTerminalWriter
 
 
-class TerminalWriter(BaseTerminalWriter):
+__all__ = [
-    def _write_source(self, lines: List[str], indents: Sequence[str] = ()) -> None:
+    "TerminalWriter",
-        """Write lines of source code possibly highlighted.
+]
-
-        Keeping this private for now because the API is clunky. We should discuss how
-        to evolve the terminal writer so we can have more precise color support, for example
-        being able to write part of a line in one color and the rest in another, and so on.
-        """
-        if indents and len(indents) != len(lines):
-            raise ValueError(
-                "indents size ({}) should have same size as lines ({})".format(
-                    len(indents), len(lines)
-                )
-            )
-        if not indents:
-            indents = [""] * len(lines)
-        source = "\n".join(lines)
-        new_lines = self._highlight(source).splitlines()
-        for indent, new_line in zip(indents, new_lines):
-            self.line(indent + new_line)
-
-    def _highlight(self, source):
-        """Highlight the given source code if we have markup support"""
-        if not self.hasmarkup:
-            return source
-        try:
-            from pygments.formatters.terminal import TerminalFormatter
-            from pygments.lexers.python import PythonLexer
-            from pygments import highlight
-        except ImportError:
-            return source
-        else:
-            return highlight(source, PythonLexer(), TerminalFormatter(bg="dark"))

src/_pytest/_io/terminalwriter.py

@@ -5,6 +5,7 @@ import sys
 import unicodedata
 from functools import lru_cache
 from io import StringIO
+from typing import Sequence
 
 
 # This code was initially copied from py 1.8.1, file _io/terminalwriter.py.
@@ -191,6 +192,39 @@ class TerminalWriter:
         self.write(s, **kw)
         self.write("\n")
 
+    def _write_source(self, lines: Sequence[str], indents: Sequence[str] = ()) -> None:
+        """Write lines of source code possibly highlighted.
+
+        Keeping this private for now because the API is clunky. We should discuss how
+        to evolve the terminal writer so we can have more precise color support, for example
+        being able to write part of a line in one color and the rest in another, and so on.
+        """
+        if indents and len(indents) != len(lines):
+            raise ValueError(
+                "indents size ({}) should have same size as lines ({})".format(
+                    len(indents), len(lines)
+                )
+            )
+        if not indents:
+            indents = [""] * len(lines)
+        source = "\n".join(lines)
+        new_lines = self._highlight(source).splitlines()
+        for indent, new_line in zip(indents, new_lines):
+            self.line(indent + new_line)
+
+    def _highlight(self, source):
+        """Highlight the given source code if we have markup support"""
+        if not self.hasmarkup:
+            return source
+        try:
+            from pygments.formatters.terminal import TerminalFormatter
+            from pygments.lexers.python import PythonLexer
+            from pygments import highlight
+        except ImportError:
+            return source
+        else:
+            return highlight(source, PythonLexer(), TerminalFormatter(bg="dark"))
+
 
 if win32_and_ctypes:
     import ctypes  # noqa: F811